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Redis implements that each service connected to websocket is bound to a unique user. Save to redis through user account = websocket fd. mysql implements the offline message pool. If a user is not online, messages sent to him by other users are temporarily stored in mysql. When the user is online, it is taken out from the offline message pool an ...

Before, I wrote a performance testing framework, which is only for testing a single HTTP interface. The business interface and non HTTP interface can't be adapted yet. Just when the front-end time is used, I updated my testing framework. This time, it is no longer based on the request, but on the method, so that the singularity can be avoided. ...

1. JDBC <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-jdbc</artifactId> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <scope>runtime</scope> </depend ...

SQL MODE is a system variable in MySQL, which can be composed of multiple modes. Each MODE controls a behavior, such as whether to allow the divisor to be 0, and whether to allow the value of '0000-00-00' in the date. Why should we pay attention to SQL mode? First, look at three simple demos (MySQL 5.6). 1. mysql> create table t1(c1 da ...

Well, I've missed 10-11 before. No wonder I started to look confused when I saw 6.5 in the video   Continue class GoodsListViewset(mixins.ListModelMixin, viewsets.GenericViewSet): """ //Product list page """ serializer_class = GoodsSerializer pagination_class = GoodsPagination # Because GenericViewSet also ...

First, introduce some basic operations of SQL database: 1 create 2 delete 3 write 4 update (modify) 5 condition selection With the above basic operations, you can establish and store a simple database.   Release the code called by python: here is calling dos to operate the database, which is not as simple as the following # -*- coding: u ...

Catalog Database connection pool pymsql linked database Database connection pool version Database connection pool pymsql linked database import pymysql conn = pymysql.connect(host='127.0.0.1', port=3306, user='root', passwd='123456', db='s8day127db') cursor = conn.cursor(cursor=pymysql.cursors.D ...

I. common statements of DDL, DML and DCL 1. DDL (Data Definition Language) database definition language (1) database schema definition #Create database create database if exsites db_name; #Selected database use db_name; #Delete database drop database if exists db_name; #modify the database alter database db_name set ...; #S ...

I. installation Hive installation: brew install hive mysql installation: brew install mysql Start MySQL: bash mysql.server start 2. Metabase configuration Hive uses derby as the metabase by default. Here we use mysql to store metadata, and do some initialization configuration below Log in to mysql: mysql -u root ...

Basic information Main storehouse: Database 2 10.126.4.2 Database 3 10.126.4.3 1. Stop database 3 external service Prevent services from writing data through database 3 during synchronization $ firewall-cmd --remove-port=3306/tcp $ firewall-cmd --add-rich-rule="rule f amily="ipv4" source address="10.126.4.2" port protocol="tcp" port="3306" a ...